Monday 19th of October 2020


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A Load line is a document generally issued by a classification society allowing vessels to carry cargo at sea and/or to make foreign voyages. Vessels with load lines will have the characteristic “Plimsoll Mark” attached amidships on each side of the hull.


In the United States the American Bureau of Shipping (ABS) issues load line certificates on behalf of the United States Coast Guard. The certificates require that a vessel be built to load line standards and that the vessel undergoes both initial and follow up inspections, generally on an annual basis with haulout inspections every fifth year.

The regulations requiring load lines are contained in 46 CFR (Code of Federal Regulations).

46 CFR 42.03-5(a) requires any vessel engaged in foreign voyages or international voyages, other than solely Great Lakes voyages, have a load line except for:

  • Warships.
  • New vessels of less than 79 feet in length; (new vessel defined as keel laid on or after 7/21/1968).
  • Existing vessels of less than 150 gross tons (GT).

46 CFR 42.03-5(b) requires any vessel which engages in domestic voyages by sea (coastwise and intercoastal voyages) have a load line except for:

  • Merchant vessels less than 150 gross tons.
  • Vessels which are mechanically propelled and numbered by a State or the Coast Guard under the Federal Boat Safety Act of 1971.
  • Pleasure craft not used or engaged in trade or commerce.
  • Barges of less than 150 gross tons.
  • Vessels engaged exclusively in voyages on waters within the United States or its possessions and which are determined not to be “coastwise” or “Great Lakes” voyages (i.e. San Francisco Bay).
  • Warships.
  • U.S. public vessels other than those vessels of 150 gross tons or over and engaged in commercial activities.


In other words, if your tugboat was built after July 21, 1968, and is less than 79’, OR it was built prior to that date and is less than 150 gross tons, there is no load line necessary to make a foreign voyage.

Or, if your barge is less than 150 gross tons then there is no load line necessary to make a coastal voyage (meaning transiting up or down the coast outside of the line of demarcation).

It is pretty common for tugs to be less than 150 GT. However, it is much less common for a barge of any size to be less than 150 GT. This is because gross tonnage is a measurement tonnage of 100 ft3. So if you have a barge that is 200’ long by 50’ wide by 10’ deep you can ballpark the GT by multiplying the dimensions together, applying a 25% deduction for the rake ends, then dividing by 100. So the 200x50x10 barge above would be roughly 750GT. Barges are de-tonnaged by adding machinery spaces, living spaces, “tonnage openings” and/or framing that would interfere with the vessel carrying cargo inside. These spaces become exempt from being tallied for the tonnage calculations.

The most significant advantage of an under tonnage barge is that load line requirements do not apply. This means that an under tonnage inland barge can be moved from one port to another, up and down the coast, without needing to obtain a USCG Temporary Certificate of Inspection (commonly referred to as a Trip Permit). This also means that the USCG is not concerned if an under tonnage barge is being used to haul cargo on a coastal voyage, or to work as a crane barge outside of the line of demarcation.

In my opinion the most important thing to keep in mind with both under tonnage boats and barges is that the vessels do not have any kind of certificate or license granting them special privileges as if it had a load line. The only reason that the vessel can be used as if it had a load line is that they are exempt from the regulations requiring one. This means that someone other than the United States Coast Guard needs to make sure that the vessel is suitable to be used in a particular manner. This most likely will fall to the Underwriter who insures the risk. Hopefully the Underwriter will assign a competent Marine Surveyor to inspect the vessel and to render an opinion that the vessel is, or is not, suitable for its intended purpose.



  1. Can load line tank barges be inspected for ABS certification.

    • admin says:

      Since ABS is the entity that issues load lines (at least for US vessels) a load line barge by definition is already inspected by ABS. Does that answer your question?

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